A significant recent health care development is the realization that the effect diseases have on patients' quality of life is a health care outcome of crucial importance. Although skin diseases are common and cutaneous symptoms can be debilitating, no outcome measure exists to gauge accurately effects of skin disease on patients' lives. The long-term objective of this application is improvement in patient outcomes of skin disease. The immediate goal is the development of a skin health status instrument which is reliable and valid for discriminative and evaluative comparisons. As preparation, a conceptual framework was developed for skin disease impact on patients' lives, and a prototype 61- item survey instrument (SKINDEX) was composed and tested in pilot studies.
The specific aims of this application are (1) to refine SKINDEX, (2) to determine its psychometric properties, and (3) to determine its sensitivity to clinical change. The research plan has four phases. In the Refinement Phase, SKINDEX will be refined based on pilot results. The Psychometric Testing Phase will study responses to SKINDEX of a cross-sectional sample of 1050 patients with skin disease: this sample size will assure stable factor analyses on an instrument of this size both in the entire sample and in important subsets. To test if SKINDEX has reproducibility, the correlation will be determined between the first 50 patients' responses one week apart. In the remaining 1000 patients, to test if SKINDEX has internal consistency reliability. Cronbach's coefficient alpha will be calculated for construct scores from the conceptual framework. To test if SKINDEX has evidence of construct validity, factor analysis will be used to determine if factors quantitatively represent the constructs in the conceptual framework. In the Reproducibility Phase, SKINDEX will be administered sequentially over six months to 785 patients with skin disease. Patients' responses during treatment will be correlated with changes they report to global questions about effects of their disease. Power calculations indicate that this sample size is sufficient to detect a clinically meaningful change in factor scores over time. In the Applications Phase, SKINDEX will be used as a health outcome for studying the quality of dermatologic care. The relationship between this outcome and characteristics of patients, physicians, and treatments will be determined. Capitalizing on institutional strengths in outcomes assessment, psychometrics, and investigative dermatology, this application also presents a career development path which parallels the development of the health status measure. At the end of this award, the principal investigator will have gained the insight and research skills necessary to use SKINDEX in studies to advance understanding of the quality of dermatologic care.
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